var url = 'http://requestb.in/1d03gpm1';

var body = 'rand=';

var button = document.getElementById('mkReq');

var msg = document.getElementById('msg');

var randToken = Math.ceil(Math.random() * 1000000);

​

msg.innerHTML = 'token '+ randToken;    

​

function echo (e) {

  if (e.target.readyState === 4) {

    msg.innerHTML = randToken + ' Success';

  }

}

​

function callOtherDomain(){

  var invocation = new XMLHttpRequest();  

  invocation.open('POST', url, true);

  invocation.onreadystatechange = echo;

  invocation.send(body + randToken); 

  msg.innerHTML = randToken + ' Sending...';

}

​

​

button.addEventListener('click', callOtherDomain);